In full duplex (FD) communications, downlink (DL) transmissions (e.g., from an access point (AP) to a station (STA)) and uplink (UL) transmissions (e.g., from a STA to an AP) can take place simultaneously.
In symmetric FD communications, the same two nodes are involved in both DL transmission and UL transmission. For example, an AP sends DL transmissions to a STA and the same STA sends UL transmissions to the AP. Because the same pair of nodes is involved in both the DL and UL transmissions, issues of synchronization of the DL and UL transmissions can be addressed in a relatively straightforward manner.
In asymmetric FD communications, DL transmission occurs between one pair of nodes (e.g., the AP and a first STA), but UL transmission involves a different third node (e.g., the AP and a second STA). The first STA and second STA may not be synchronized, and the DL transmission and UL transmission may interfere with each other. It would be desirable to provide an improved way to coordinate such FD communications, for example a way for the AP to coordinate timing of the DL and UL transmissions.